Continuous Regeneration of Ceramic Particulate Filter in Stationary Diesel Engine by Nonthermal-Plasma-Induced Ozone Injection

Every year, stricter regulations are imposed on diesel engine emissions. It is difficult to satisfy these regulations only by improving the combustion improvement techniques in the near future. We require highly effective postprocessing technology for the removal of particulate matter (PM) such as carbonaceous particulate from diesel engine emissions. Ceramic diesel particulate filter (DPF) technology has emerged as a leading technology for the removal of PMs. However, PM incineration or regeneration is a major problem encountered in the use of DPFs at low temperatures. In this paper, pilot-scale experiments are conducted for regenerating the DPF in a stationary diesel engine generator by nonthermal-plasma-induced ozone injection at low temperatures and atmospheric pressures. In this process, NO₂ and O₃ produced by a plasma reactor are used for the incineration of PMs accumulated on the DPF. The regeneration experiment is conducted by using a small diesel engine and a surface-discharge-type plasma ozonizer. The amount of O₃ required for the continuous regeneration of the DPF is determined under different operating conditions of the engine. It is confirmed that the difference between pressures upstream and downstream of the DPF or the pressure difference decreases only when the plasma is turned on, and the DPF is regenerated at approximately 250degC. The plasma energy required for DPF regeneration is only 0.25% of the power generated by the engine.